Chilling graffiti found in the bathroom of a jet due to take off from Newark Airport was inexplicably erased by a cleaner after the Transportation Safety Administration waited 47 critical minutes to contact cops, Port Authority sources told The Post yesterday.

“By the beard of Mohamed and mighty sword of Allah,” read the message found on a Continental Airlines jet Saturday night. It was scrawled in black ink, just above the mirror.

The message was discovered by a flight attendant who took a cellphone picture and notified the captain. He called his operations center, which notified the TSA.

Port Authority cops said they didn’t hear from the TSA for 47 minutes. The TSA said it notified the PA “within a few short minutes.”

During the delay, passengers got off the Little Rock, Ark.-bound jet and a cleaner scrubbed off the message, The Post’s sources said.

“The delay severely compromised the integrity of a crime scene,” said one PA police official.